<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
  <style>
    ul li {
      list-style: none;

    }
    .item{
      width: 100px;
      height: 40px;
      background: pink;
      border: 1px solid rgb(246,102,57);
      text-align: center;
      line-height: 40px;
      float: left;
    }
    /* 1 */
    /* .clearfix{
      clear: both;
    } */
    
    /* 2 */
    .list::after{
      content: '';
      display: block;
      clear: both;
    }
  </style>
</head>
<body>
  <ul class="list">
    <li class="item">1</li>
    <li class="item">2</li>
    <li class="item">3</li>
    <li class="item">4</li>
    <li class="item">5</li>
    <!-- <li class="clearfix"></li> -->
  </ul>
  <div class="test">hello world</div>
</body>
</html>